The present disclosure relates generally to a cylinder head for use with an internal combustion engine, and more particularly to a cylinder head having a recess separating a combustion chamber flame deck from a cylinder block-engaging portion.
A typical internal combustion engine includes a cylinder block, a cylinder head attached to the block, one or more pistons, and one or more combustion chambers. The cylinder block has at least one cylinder bore containing a cylinder liner, and each piston is slidably positioned within each cylinder liner. The cylinder head has a body, and the body, the piston, and the cylinder liner define the combustion chamber.
A typical cylinder head for an internal combustion engine is formed by a casting process and has an inner wall, an outer wall, and sidewalls. The cylinder head is designed to control gaseous flow from intake manifolds in the cylinder head to the combustion chamber and from the combustion chamber to exhaust manifolds in the cylinder head. The cylinder head may have three regions, commonly referred to as an upper deck, a middle deck, and a lower deck. The lower deck is mounted to the cylinder block adjacent to, and partially defining, one or more of the combustion chambers. Generally, the gaseous flow passes through the lower deck of the cylinder head. If required, the cylinder head may support a fuel injector and a firing mechanism for each combustion chamber of the internal combustion engine. Because each of these requires openings to the combustion chamber through the lower deck, there are areas on the lower deck subject to increased levels of heat and stress that develop during the combustion process.
As a result of the operation of the internal combustion engine, the combustion chamber, cylinder head, and piston, as well as other areas of the cylinder block are exposed to high levels of heat. The heat creates thermal gradients through the engine that result from heat of the combustion process and a cooling system process. The thermal gradients can create localized stress regions and hot spots within the lower deck of the cylinder head that have the potential to alter the alignment of the valves, the fuel injector, the firing mechanism, and other components in the engine, which can cause the engine to operate in a less than ideal manner. In addition, with the lower deck of the cylinder head experiencing these stresses, the lower deck has the potential to deform or crack.
Generally, fluid flow paths have been provided in the cylinder head to draw heat from the hot spots. The use of the flow paths as cooling fluid passageways assists in maintaining the cylinder head near a uniform temperature and reduces the likelihood of fracturing as the cylinder head temperature fluctuates. U.S. Pat. No. 4,690,104 (“Yasukawa”) describes one such type of cylinder head. Yasukawa is directed to a cylinder head that provides plugs to speed up coolant flow in regions of large cross-sectional areas. In addition, Yasukawa provides several fins located on boss portions for securing the cylinder head to the cylinder block, as well as on cylindrical walls that connect the intake and exhaust valves to the combustion chamber.
One drawback to Yasukawa is that neither the plugs nor the fins provide additional rigidity to the inner walls of the cylinder head. As a result, the inner walls have the potential to experience problems with a lack of stiffness and failure because of the cyclic loadings created by combustion of fuel in the combustion chambers. Additionally, Yasukawa does not provide cooling fluid flow in certain areas of the engine that are likely to have the highest temperatures.
The present disclosure is directed to overcoming one or more of the problems or disadvantages existing in the prior art.
In one aspect, a cylinder head is provided. The cylinder head includes an upper deck, a lower deck, and a sidewall. The sidewall extends between the upper deck and the lower deck. The lower deck of the cylinder head defines a block-engaging portion and a combustion chamber flame deck. The combustion chamber flame deck is spaced apart from the block-engaging portion of the lower deck.
In another aspect, an engine is provided. The engine includes a cylinder block having a cylinder bore, and a piston slidably positioned within the cylinder bore. A cylinder head is also provided and has a lower deck connected to the cylinder block. The lower deck defines a block-engaging portion and a combustion chamber flame deck. The combustion chamber flame deck is spaced apart from the block-engaging portion by a recess.
Referring now to the drawings, there is illustrated in
The cylinder head 14 of the engine 10 includes a body 28. The body 28 is defined by an upper deck 30, a lower deck 32, and a sidewall 34 extending between the upper deck 30 and the lower deck 32. A portion of the lower deck 32 is in direct engagement with the cylinder block 12 and is referred to herein as the cylinder block-engaging portion 36. The block-engaging portion 36 is a generally planar surface as can be seen more clearly in
Also shown in
Also shown in
As stated above, the portion of the lower deck 32 that is located above the cylinder bore 16, and defines an upper portion of the combustion chamber 24, is the combustion chamber flame deck 26. Formed within the combustion chamber flame deck 26 is a plurality of orifices, indicated generally at 50. Illustrated in
An intake valve 60 and an exhaust valve 62 is disposed within a separate intake valve chamber 64 and an exhaust valve chamber 66 formed in the body 28 of the cylinder head 14, as shown in
A fuel injector 68 is also positioned within the body 28 of the cylinder head 14. A fuel injector opening 70 in the combustion chamber flame deck 26 allows fuel to be passed into the combustion chamber 24 via the injector 68. As shown, the fuel injector 68 is centrally positioned within the combustion chamber flame deck 26. The detailed operation of the intake valves 60, exhaust valves 62 and fuel injector 68, in accordance with the operation of the engine 10, is generally known in the art and will not be described in further detail. As is also known, the operation of the engine 10 causes combustion within the combustion chamber 24. This in turn causes the generation of heat and pressure, which can result in stresses acting upon the lower deck 32 of the cylinder head 14. It should be appreciated that the invention could be configured to work with a spark-ignited engine by including a spark plug orifice and spark plug in the combustion chamber flame deck and cylinder head, respectively.
Also shown in
Illustrated in
It can be appreciated that the recess 72 can have any size, shape, width, and height. As shown, the recess 72 has a generally triangular cross-sectional shape. However, it should be appreciated that the recess 72 could have a half-oval, semi-circular, or rectangular shape as well. The recess 72 has a depth, D, into the lower deck 32 of the cylinder head 14 thereby providing a separation between the remaining portion of the lower deck 32 and the combustion chamber flame deck 26. The extent to which the recess 72 extends into the body 28 of the cylinder head 14 can depend on several design criteria including structural requirements of the cylinder head 14 or the engine 10, the amount of heat and pressure the cylinder head 14 will be subjected to, the size and performance requirements of the engine 10, and the location and size of fluid jackets within the cylinder head 14. One skilled in the art can appreciate that many other design factors can be considered when determining the exact size and shape of the recess 72.
In
Referring again to
Alternatively, or additionally, fluid could flow out of the recess via a fluid exit port 88 (shown schematically in
When the fluid exits the recess 72, the fluid flows into the cylinder head fluid jacket 44 formed in the body 28 of the cylinder 14. The body 28 of the cylinder head 14 can define one or more fluid jackets. In the illustrated embodiment, the cylinder head fluid jacket 44 defines a lower portion 90 and an upper portion 92. The lower portion 90 surrounds the valve chambers 64, 66 and allows a coolant fluid to pass through the lower portion 90 in order to remove heat from an upper portion 25 of the combustion chamber flame deck 26, the first and second orifices 52, 54, and the exterior surfaces of the fuel injector 68. Fluid then flows into the upper portion 92 of the fluid jacket 44, further cooling the exhaust ports and intake ports of the cylinder head 14 and then out of the cylinder head 14, eventually before continuing on to a heat exchanger (not shown). It should be appreciated that the fluid can be directed to flow into any portion of the fluid jacket 44 in any order. Using the cooling fluid line 40 and the first fluid conduit 84 can allow for accurate control of the amounts of fluid being supplied to each area of the cylinder head 14 to facilitate cooling. For example, sixty-five percent (65%) of the fluid flow could be through the cooling fluid line 40 so that the majority of the fluid reaches the cylinder head fluid jacket 44. The remaining fluid, thirty-five percent (35%), could be directed into the cylinder fluid jacket and then into the recess 72, and eventually into the lower portion 90 of the cylinder head fluid jacket 44. It should be appreciated that these amounts are exemplary only, and that any amount of fluid flow can be directed through the various fluid passageways.
It should be appreciated that seals 114 and other mechanisms can be used to prevent the fluids from passing into the combustion chamber 24 and into the various openings 42, 52, 54, and 70 on the block-engaging portion 36 and in the combustion chamber flame deck 26. The exact materials, structure, shape, and location of such sealing mechanisms are not described in detail as they are generally known in the art, or their use would be evident to one skilled in the art.
In the operation of an engine 10, high levels of heat are generated within the combustion chamber 24. The heat is transferred throughout the engine 10 and its components. As is known in the art, fluids are used as coolants to transfer heat from these surfaces. Various chambers and fluid jackets are included in engines to contain and carry the cooling fluids within and around the engine 10. According to the present invention, fluid flow to and within the recess 72 also acts to cool portions of an engine 10 that are not typically cooled.
As is also known, due to the high heat and pressures, a large amount of stress is placed on the combustion chamber flame deck 26. To provide increased structural support, the recess 72 separates the combustion chamber flame deck 26 from the rest of the lower surface of the cylinder head 14. This allows the inner support wall 35 to directly connect the outer periphery 27 of the combustion chamber flame deck 26 to the sidewall 34. By providing direct support at a region of the cylinder head 14 that is subject to high stress (bending stress, as well as other mechanical stresses) the structural integrity of the cylinder head 14 is increased. Since the recess acts as a break between the combustion chamber flame deck 26 and the lower end 38 of the sidewall 34, the inner support wall 35 is angled relative to the plane of the lower deck 30 of the cylinder head 14. Therefore, the inner support wall 35 is supported on the sidewall 34 at a point above the lower end 38 of the sidewall 34. Such a structure is a result of the lower deck 32 of the cylinder head 14 being separated into distinct portions by the recess 72. Although the inner support wall 35 is being described as a connector between the combustion chamber flame deck 26 and the cylinder head body 28, it should be appreciated that the cylinder head 14 is typically cast as a unitary structure and that there is no separate connection required between the inner support wall 35 and the sidewall 34. However, it should also be appreciated that any suitable process can be used to create the inner support wall 35 and connect it between the outer periphery 27 of the combustion chamber flame deck 26 and the sidewall 34. This structure is common to each of the embodiments described herein. It should also be appreciated that that inner support wall 35 could be angled, arced, or be straight (generally vertically oriented in the embodiment shown in the Figs.) and directly connect with the upper deck 30 of the cylinder head 14 if it is so desired. Such configurations all act to directly support the outer periphery 27 of the flame deck 26 with the rest of the cylinder head 14.
It should be appreciated that the implementation of the recess 72 can “short circuit” the conduction of heat along the entire lower deck 32 of the cylinder head 14. In addition to the recess 72 separating the combustion chamber flame deck 26 and the block-engaging portion 36, therefore acting as a mechanical break in the conduction path of heat generated by the engine 10, if fluid is flowing within the recess 72, then the heat is being transported away from the heated surfaces, thereby decreasing the heat conduction from the combustion chamber flame deck 26 to the block-engaging portion 36 of the cylinder head 14. Such a break in the heat conduction path also limits the amount of heat that affects the seals 114 surrounding the combustion chamber flame deck 26 and particularly the outer seals 114 between the cylinder block 12 and the cylinder head 14. Therefore, the integrity of the seals 114 can be improved by the additional dispersal of heat. Since heat is being rejected from the combustion chamber flame deck 26, the first and second orifices 52, 54 can be isolated from some of the heat as well. This has the potential to prevent distortions of the orifices 52, 54 that may be caused by heat and stress within the combustion chamber 24.
The design of the recess 72 also allows for thermal expansion of the combustion chamber flame deck 26. Due to the large amount of heat generated during the operation of an engine 10, the metal components of the engine 10 could expand (in very small amounts). Therefore, the recess 72 gives the combustion chamber flame deck 26 space to expand without affecting the remaining portion of the lower deck 32 of the cylinder head 14. This also reduces the internal stresses in the cylinder head 14 since these areas have the room to expand rather than perpetuating the stress throughout the body 28 of the cylinder head 14. In addition, if any gases from within the combustion chamber 24 were to escape past the seals 114, the recess 72 provides an area in which the gases can expand and cool. Allowing the gases to expand and cool in this manner also helps to prevent the blow out of a seal 114 between the lower end 38 of the sidewall 34 and an upper surface of the cylinder block 12.
It was stated above that the recess 72 could be designed based on many factors. One consideration in the design of the recess 72 is the desired amount of cooling around the combustion chamber flame deck 26. This is because the recess 72 can be used to assist with the heat rejection function of the engine 10 in combination with the various fluid jackets 20, 44 and flow paths described herein and illustrated in the Figures. The recess 72 can be configured to receive a fluid from the fluid jacket 20 of the cylinder block 12. Such fluid communication can be either direct or indirect, as will be explained below.
In the embodiment illustrated in
It should be appreciated that the use of the drillings 43, the cooling fluid line 40 and the recess 72 to carry a fluid to assist with the cooling of the interior portions of the cylinder head 14, can also be used to control the amount of fluid that is directed to specific locations. For example, if additional cooling is required around the combustion chamber flame deck 26 the flow through the first fluid conduit 84 could be increased while the flow through the cooling fluid line 40 is reduced. Similarly, drillings 43 could be added or removed depending on whether cooling around specific orifices (only intake valve seats or exhaust valve seats) is desired.
Illustrated in
In an alternate embodiment, such as that shown in
In another alternate embodiment of the cylinder head 106 shown in
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects, objects, and advantages of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
3882842 | Bailey et al. | May 1975 | A |
4690104 | Yasukawa | Sep 1987 | A |
4763619 | Eitel | Aug 1988 | A |
5207210 | Yamagata et al. | May 1993 | A |
5575251 | Bock | Nov 1996 | A |
5970941 | Bock | Oct 1999 | A |
6116198 | Kirtley et al. | Sep 2000 | A |
6164260 | Bock | Dec 2000 | A |
6205974 | Yonezawa et al. | Mar 2001 | B1 |
6234134 | Bedapudi et al. | May 2001 | B1 |
6295955 | Kato et al. | Oct 2001 | B1 |
6705269 | Fukuzawa et al. | Mar 2004 | B2 |
6732698 | Bedwell et al. | May 2004 | B1 |
6925981 | Ibukuro et al. | Aug 2005 | B2 |
Number | Date | Country |
---|---|---|
0 550 422 | Jul 1993 | EP |
58-143149 | Aug 1983 | JP |
62-142850 | Jun 1987 | JP |
10-220286 | Aug 1998 | JP |
WO 2005042955 | May 2005 | WO |
Number | Date | Country | |
---|---|---|---|
20070240670 A1 | Oct 2007 | US |